Concentrated or diluted heparin prophylaxis of postoperative deep venous thrombosis

Abstract

A concentrated and a diluted heparin solution (Vitrum AB) have been evaluated in a controlled blind study, using a standard dosage of 5000 IU, given every 12 hours subcutaneously, 167 patients undergoing abdominal surgery were randomized into three groups: 63 received diluted heparin 5000 IU/ml, 43 received concentrated heparin 25000 IU/ml and 61 patients served as controls. 80 per cent of the patients suffered from malignant disease. Deep venous thrombosis (DVT), diagnosed with the 125I-fibrinogen method, was found in 16% of the patients receiving diluted heparin, in 23% of those receiving concentrated heparin and in 33% of the controls. To evaluate the amount injected, an in vitro experiment was performed in which the intended dose was 5000 IU. The measured amount of the concentrated heparin solution was significantly less than 5000 IU. It is concluded that the frequency of DVT after gastrointestinal operations can be reduced significantly (in the present study from 33 to 16%) by administering diluted calcium heparin every 12 hours for 6-8 days. The concentrated heparin solution did not significantly reduce postoperative DVT, possibly on account of variations in the dosage. Diluted heparin prophylaxis can be achieved without serious side effects.